AP Photo/James D SmithCowboys LB Sean Lee was actively involved in every Panthers possession on which he participated.

DeMarcus Ware is an elite outside pass rusher for the Cowboys who keeps tackles and defensive coordinators up at night. Jay Ratliff is an imposing force at nose tackle.

Lee is nearly everything else.

His season is done. Lee will need season-ending surgery on his right big toe, sources told ESPNDallas.com. We won't know how long he'll need to recover, or if he'll even be the same player when he returns.

Felix Jones underwent toe surgery in 2008, and it took him a while to regain his explosiveness. This is not to say Lee won't return to his former self, but the Cowboys are heading into the Murderers' Row portion of their schedule. Lee's absence should concern defensive coordinator Rob Ryan.

Jason Garrett, too, for that matter. The Cowboys coach's one-game-at-a-time mantra is needed at Valley Ranch, and Lee is one of its main disciples.

The young inside linebacker buys into the message and spreads it across the locker room. His play on the field is contagious, too.

If you don't believe it, check the numbers: He's third on the team with eight quarterback pressures this season, is tied for second with two tackles for loss, has one of the four forced fumbles, one of the two interceptions and two pass breakups.

Before he went down in the win over the Carolina Panthers, he made a play on every possession in which he participated -- five possessions, five tackles, one pass breakup and one tackle for loss.

Tim Heitman/US PresswireSean Lee's stats show he's among the Cowboys' leaders when it comes to big defensive plays.

Now, forget about the numbers for a minute.

He calls the signals for Ryan's defense. We're not saying Lee is perfect, but like Ware and Ratliff, he's close to it.

The Cowboys will have to fill the void with veteran Dan Connor and second-year pro Bruce Carter. Connor took over the weakside inside linebacker spot against Carolina and fared well. Carter replaced Lee as the signal-caller and was good.

"It's a long season, a grind and guys get nicked up," Connor said. "I don't think I've ever been on a team where guys have been able to stay healthy, every play the whole year. It's all about being ready and waiting on your opportunity and helping the team."

Lee's injury is so serious he couldn't put on his dress shoes as he left Sunday's game. He wore sneakers.

"I couldn't push off the way I needed too," Lee said. "I couldn't do my job the way I needed to, but I knew we had guys who were ready to roll and who could do a better job than I could in the state that I was in."

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What makes things harder is the New York Giants haven't lost in their three visits to Cowboys Stadium.

"It won't even be on my mind at all," Ware said. "I don't care if they won every single time here at our stadium, we've got to find some way to beat them and win the game and we have an opportunity to do that this week."

It's going to be done without Lee as the Cowboys play two of their next three games on the road.

Someone has to emerge in his absence or pick his game up even more.

"We've got to dominate every week on defense," Ware said. "It's not just once a week. You have to be committed in what you do and hold teams to low points [and] that's what great defenses do, just go out and get the job done."